A single use, self-contained, self-powered disposable oximeter, in the form of a patch or a bandage strip, has mounted thereto a light emitter and a light sensor that together measure at least the SpO2 of the patient. A quadrilateral active area is disposed in the scribe line region, with four equilaterals and four vertex angles. An important criteria of the invention is that the lubricant blend of polyol ester and alkylbenzene are sufficiently miscible with the hydrofluorocarbon refrigerant blend both as a liquid and a gaseous refrigerant over the operational temperatures of the compression refrigeration system. A channel on one end of the grounding bar includes a slotted headless set screw for establishing a secure connection to an existing ground wire.